How continuous sound becomes digital samples
Digital audio represents a changing signal as measurements taken at regular intervals. The sample rate tells you how many measurements are taken each second, while bit depth controls the available numerical levels. These describe different limits: timing detail and how finely each sample's amplitude can be represented.
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Measure, round and store
A microphone converts sound into a changing electrical signal. An analogue-to-digital converter measures that signal repeatedly and assigns each measurement a number.
The sample rate describes how frequently measurements occur. The bit depth describes the number of representable levels available for each sample. More levels allow smaller differences in amplitude to be represented.
Before sampling, filtering limits frequencies that would otherwise be misrepresented as lower ones, a problem called aliasing.
- Sampling divides the signal along time.
- Quantisation maps measurements to available numerical levels.
- Playback converts the stored values back into a changing signal.
Increasing one setting does not repair every recording problem. More samples cannot remove background noise already captured by a microphone, and greater bit depth does not correct a badly positioned microphone.